Aqueous fractionation of wood has been proposed as a suitable processing method for biorefineries. When treatments are performed under low severity conditions, water-soluble components (which could be detrimental in further processing stages) are removed, whereas polysaccharides, lignin, and other water-insoluble constituents remain in solid phase with little alteration. In order to explore the presence of added-value products in aqueous extracts from Pinus pinaster wood, different samples (heartwood and sapwood with and without knots) were extracted with water at 130 to 140 °C, and the resulting solutions were assayed for yield and composition (by GC-FID, GC-MS, and HPLC). The major extract components, such as polysaccharide-derived products, simple phenolics, stilbenes, lignans, flavonoids, organic acids, jubaviones, steryl esters, and triglycerides, were identified and quantified. In order to assess a possible application of the extracts, their antioxidant activity was measured using the Trolox Equivalent Antioxidant Capacity assay.